IIRC, I connected the white wire in the head light shell to the black wire on an SAE, and the red wire to the ground , also in the headlight shell. I would not recommend using this for the heated gear though. In my case I only use it for low current draw, ie. GPS.
Now remember I have a MKIII, so there is a lot of wires in the headlight shell, unlike the other years. Pretty sure the white wire coming from the ignition switch (which is switched power) is pretty standard for all the Commando's. That's why I use my Battery Tender SAE for my heated stuff, it's a decent gauge wire directly from the battery, and if I blow a fuse nothing else is affected.
Don't get too wrapped up in the (+) earth thing, as long as what ever you hook up is isolated it is (+) to (+) and (-) to (-) when making your connections.
Glad you heated stuff worked well.
Pete
www.revzilla.com
